Control device for wireless signaling.



E. H. COLPITTS.

CONTROL DEVICE FOR WIRELESS SIGNALING.

APPLICATION FILED SEPT. I6. 1915.

1,1.98,700 lntentedSept. 191, 1916.

-mmm mlm UNITED STATES PATENT oEEIcE.

EDWIN H. COLPITTS, 0F EAST ORANGE, ERSEY, ASSIGNOR, BY lIMIESNE ASSIGN-MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEWYORK.

CONTROL DEVICE FOR WIRELESS SIGNALING.

Speccation of Letters Patent.

Application led September 16, 1915. Serial No. 50,966.

To all 'whom it may concern.'

Be it known that I, EDWIN H. CoLPI'I'rs, a subject of the King of GreatBritain, residing4 at `East Orange, in the-county of Essex and State ofNew Jersey, have invented certain new and useful Improvements in ControlDevices for Wireless Signaling,` of which the following is a full,clear, concise, and exact description.

`This invention relates to the control for signaling purposes of thelarge current obtained from the output circuit of a thermlonicamplifier. A

The object is to reduce the power consumption to a minimum or smallvalue 'and to obtain a maximum output from a'given amount of apparatus.The result sare obtained by so arranging the circuit that the spacecurrent flows in the amplifier tubes only during the time that signalimpulses are being sent. This might be accomplished by making andbreaking lthe output or'lngh power circuit of theamplifier, but this1nvolves the interruption or breaking of a circuit in which a largecurrent at a highpotent-ial maybe flowing. The desired result can beobtained better by an arrangement by means of which the voltageof thebat-- tery in the input 'or grid circuit has such a value that the spacecurrent, that is, the current inthe output circuit, is made very small.In other words, provision is made whereby the voltage applied to thegrid or input circuit of the amplier is changed at the instant ofsignaling from such a ,value as causes a minimum energy loss intheoutput circuit to a value 'which permits of normal fiow of current inthe said circuit. Thismay be accomplished in a variety of ways and veryreadily for the reason that the normal power absorbed in the inputcircuit of a thermionic amplifier is very small.

Figure 1 of the drawing shows one arrangement of circuits by which thedesired result is obtained;l Fig. 2 shows a modified circuit.

Referring to the figures, 1 represents an inductance deriving highfrequency oscillations of low power in a manner hereafter described andwhich is connected to the input circuit of a thermionic amplifier 3; theelectrode 5 of said amplifier being the heated element and the electrode4 being the usual the plate electrode 6 through the tuning condenser 2,the inductance 8 and the filament 5. In parallel to the inductance 8 isthe powerbattery 7 land choke coil 24. For signahngpurposes, theinductance 8 is inductively connected to the inductance 9 whlch, Inturn, is connected to the signaling system. This signaling system mayconsist of any wire system or of a radiating'antenna to be used forspace telegraphy as shown in the figures, in which 10 represents theelevated antenna lor other suitable radiating system and 11representsthe usual earth connection for such a system.-

'Connected to the input terminals of the taining the inductance 1, is acircuit con taining a battery 12, whichV is the usual battery fordetermining the potential applied between the electrodes 4 and 5. Inthis inventlon, battery 12 has -a sufiiciently high voltage to reducethespace current flowing between In order to transmit signalingcurrents, it 1s necessary to reduce the voltage impressed on the Inputcircuit sufficiently to permit the flow of the normal space current. Inorder to accomplish this the following arrangeamplifier and in parallelto the circuit con-4 Patented Sept. 19, 1916.

the electrodes 6 and 5, from the bat-` tery 7, to zero or toa relativelysmall value.

ment is used: A switch or key y13 is placed Y 1n .the circuit of thebattery kand a large reslstance 14 of several thousand ohms or more 1splaced in shunt to this key. A conductor 15 leads from vsomeintermediate point 16 of the battery 1-2, ,the free end of saidconductor 15 being placed in juxtaposi# tion to the spring terminal 17,which also forms one terminal of the switch 13.

It has'been found desirable also, but not necessary, to placev a key orswitch 18 in the circuit of the inductance 1. ,The compound key orswitch may be operated b y hand cli-I rectly or indirectly by means ofthe magnet or relay 19. The armature 20 is rigidly secured to theoperating portions of the switch. This relay 19 may, in turn, beoperated by means of the key 21 which closes a circuit containing thesaid key, battery 22 and the winding of'the relay. In the circuit of theinductance l is placed a condenser 23. A choke coil 24 is placed inseries with the battery 7. Ay similar choke coil 25 is placed in thccircuit of the battery 12. grid. The output circuit is connected fromThe operation of the system is as follows:

When no signals are being transmitted the 110 switch 13 is closed,thereby short-circuiting the high resistance 14 and permitting thevoltage of the whole battery 12 to be impressed on the input circuit ofthe amplifier. This battery is of sufficient voltage to prevent the flowof space current between the electrodes 5 and 6. Upon closing the key21, the' switch 13 is opened and the member 17 is removed to makecontact with the terminal 26 and also to close the switch at 18.v Thisoperation brings `the point 16 of the battery 12 into electricalconnection with the terminal 4 of the amplifier. Conductor 15 is lplacedat such a point 16 of the Lbattery that the Voltage which is now `imApressed on the input circuit of the amplifier is sufficiently small topermit the normal flow of space current through the amplifier. theswitch 18 permits the transferof high frequency low power oscillationsfrom the output circuit -into the inputcircuit of the amplifier by meansof the inductance 1. The whole operation results in a fiow of amplifiedhigh frequency oscillations in the output circuit of the amplifier. Theoutput circuit containing the condenser 2 and inductance 8 is tuned tothe frequency of the radiating antenna system. The frequency of thiscircuit 2-8 and the antenna determine the period of the high frequency0scillations which are to be transmitted, and of the voscillations whichare fed back into the input circuit 'by means of the inductance 1.

The purpose of the resistance 14 is to prevent that portion of thebattery 12 which is not used when signaling from being short-circuited.The condenser 23 is to prevent the discharge of the battery 12 throughthe inductance 1, and the choke coils 24y and 25 are inserted in orderto prevent the passage of high frequency oscillations through thebattery circuits.

In Fig. 2 a modification of the output circuit is shown. In this casethe battery 7 is connected in series instead of in parallel to theinductance 8, 'and the frequency of the oscillations to be radiated, aswell as the frequency of the oscillations fedback to the input circuitVby means of the inductance 1, is determined chiefly by the period ofthe radiating antenna. In this modification battery 7 is'shunted by acondenser 28, which condenser aords a path of low impedance around thebattery 7 for the high frequency oscillations, and also forms a shortcircuit for transient high frequency 4 disturbances developed in" thebartteryiy 7 The connection for the remainderfof this system isprecisely as shown in Fig. 1.

In the specification and drawing two methods of determining the periodof the oscillations in the output circuit, and therefore in thefeed-back circuit, have been At thc same time the closing .of

shown, but it is to be understood that any ner, such, for eXample,' asshown in patent to Arnold No. 1,129,943 of March 2, 1915.v

It is obvious that the method is not limited to simple hand sending butcan ybe employed wherever the sending of signals involves an interruptedoutput.

What is claimed is.:

1. In a high frequency signaling system; a thermionic amplifier of theaudion t pe, a source of voltage connected to the input circuit of saidamplifier; a circuit deriving high frequency oscillations of a low powerfrom the output circuit of said amplifier, said circuit being connectedto the input circuit of the amplifier, and means adapted to vary theamount of voltage of the said source impressed upon the input circuit ofthe `amplifier whereby the space current is reduced to a small valuewhen not signaling.

2. In a high frequency signaling system; a thermionic amplifier of theaudion type; a circuit inductively connected to the output circuit ofsaid amplier for deriving high frequency oscillations of lowr power fromthe. output circuit of said amplifier, said circuit amplifier; a batteryconnected to the input circuit of said amplifier and a switch forvarying the amount of the batteryvoltage impressed upon the inputcircuit of the amplifier whereby the space current is reduced to aminimum or small value when not signaling.`

3. In a high frequency signaling system; a thermionic amplifier of theaudion type; a circuit inductively connected to the output circuit ofsaid amplifier for deriving hiUh frequency oscillations of low powerfrom t e output circuit of said amplifier, said circuit being connectedto the input circuit of the amplifier; a battery connected to the inputcircuit of said amplifier, said battery having sufficient voltage toreduce the space current of the amplifier to a minimum or small valueand signaling means for reducing the battery voltage impressed on theinput circuit of the amplier when signaling, to permit a large spacecurrent.

4. In a high frequency signaling system; a thermionic amplifier of theaudicn type; a circuit inductively connected to the output circuit ofsaid amplier for deriving high frequency oscillations of low power fromthe output circuit of said amplifier, said circuit being connected tothe input circuit of 100 being connected to the .input circuit of thethe amplifier; a battery connected to thel adapted, when signaling, toimpress a portion of said battery voltage upon the lnputv circuit of theamplifier.

5. In a high frequency signaling System, a thermionic amplier of theaudion type, a feed-back circuit inductively connected to the outputcircuit of said amplifier for deriving high frequency oscillations oflow power from the output circuit of said amplilier, saidcircuitbeing-connected to the input circuit of the amplifier; a batteryconnected to the input circuit of said amplifier and in parallel to saidhigh frequency circuit, and a switch adapted, when signaling, to impressa portion of the said battery voltage upon the input circuit of theamplifier and to close the feed-back circuit, and adapted, when notsignaling'to open the feedback circuit and to impress the whole batteryvoltage upon the input circuit of the amplifier, whereby the spacecurrent in the amplifier is reduced` to a minimum when not signaling.

6. In a high frequency signaling system, a thermionic amplifier of theaudion type; a feed-back circuit inductively connected to the outputcircuit of said amplifier for deriving high frequency oscillations oflow power from the output circuit of said amplifier, said circuit beingconnected to the input circuit of the amplifier, a battery connected tothe input circuit of saidv` amplier the output circuit of said and 'mparallel to said high frequency circuit, and a magnetically operatedswitch adapted, when signaling, -to' shunt a portion of the battery, toimpress the remaindery `of said battery voltage upon the input circuitof the amplier and to close the feed-back circuit, and adapted, when notsignaling, to open the feed-back circuit and to impress the wholebattery voltage upon .the input circuit of the amplifier, whereby thespace current in the amplifier is reduced to a minimum when nottransmitting signals. v Y

7. In a high frequency signaling system; a thermionic amplifier of theaudlon type; a feed-back circuit inductively connected to amplifier forderiving high frequency oscillations of low power from the out utcircuit of said amplilier, said circuit belng connected to'the inputcircuit of the amplifier; a battery connected to the input circuit ofsaid amplifier and in parallel to said high frequency circuit; a chokecoil and a resistance in series with said battery and amagneticallyoperated switch adapted, when signaling, to

open the short-circuit, to shunt a portion of said battery throughsaidjr'esistance, to impress the remainder of said battery upon theinput circuit of the ampliierA and to close the feed-back circuit, andadapted, when not signaling, to short-circuit the resistance in serieswith said batte and to open the feed-back circuit, where y the spacecurrent in the amplifier is reduced to a minimum -when not transmittingsignals.

In witness whereof, I hereunto subscribe my name this 11th day ofSeptember, A. D.

e EDWIN H. ooLPrrrs.v

